Side channel compressors, housing shells and running wheels according to the preambles of the independent claims are known, for example, from WO 00/68577 A1.
In a side channel compressor, a channel is enclosed by a housing and a running wheel. Blades are mounted on the running wheel, which project into the channel, but do not completely fill in the same. Seen in the direction of rotation of the running wheel an inlet to the channel is provided ahead of an outlet from the channel. The channel comprises two regions, namely one passed through by the blades of the running wheel, and the side channel which is not passed through by the blades. An interrupter closing the side channel is provided between the inlet and the outlet. The effective length of the interrupter has to be slightly longer than a blade distance.
The boundary surface between the side channel and the rest of the channel is frequently a plane perpendicular to the axis of rotation of the running wheel or a conical surface the axis of which coincides with the axis of rotation of the running wheel.
A fluid, frequently a gas, in particular air, enters the channel through the inlet. A part of the fluid molecules is entrained by a blade in a tangential direction. Due to the centrifugal force the fluid molecules in question are also accelerated radially outwardly and thus flow out of the blade into the side channel where they are diverted in the direction of the running wheel and undergo a further acceleration by means of the running wheel. The fluid molecules are thus conveyed on a toroidally bent helical path from the inlet to the outlet while the pressure in the fluid increases. The interrupter is to minimize the amount of fluid dragged from the outlet to the inlet.
A noise-reducing side channel compressor is known from DE 42 39 814 C2. The noise reduction is obtained by the inlet opening having a flow area which is smaller than the cross-section of the inlet piece and smaller than the cross-section of the side channel, and by a continuous course of the transition between the different cross-sections. FIG. 1 of this document shows a housing provided with outer ribs.
DE 26 10 273 C3 deals with the optimization of the ratio of the blade cell volume to the sum of the blade volume plus blade cell volume. By this the gas quantity dragged over the interrupter is reduced and the efficiency is improved.
DE 199 55 955 A1 likewise deals with an improvement of the efficiency of a side channel machine. The constructive modifications merely relate to the blades.
WO 00/68577 A1 (=EP 1 177 384 A1) claiming the priority of DE 199 21 785 A1 also deals with the improvement of the efficiency of a side channel machine. To this end, a number of labyrinth seals for sealing the gap between the running wheel and the housing have been disclosed.
It is desirable to provide a cost-effective side channel compressor.